Reproducing process



REPRODUCING PRGCESS Harry Ernest Wheeler, Naomi have Wheeler, and Caroline Wogan Durieux, Baton Rouge, La., assiguors to Board of Supervisors of Louisiana State University and Agricultural and Mechanical College, Baton Rouge, La.

No Drawing. Application March 2, 1954, Serial No. 413,716

6 Claims. (Cl. 250-406) This invention relates to the graphic arts, and more particularly to a novel process for producing prints and other reproductions.

The use of luorescent pigments in producing prints which may be exposed to a sensitized surface such as a photographic plate to produce a negative image which is in turn employed to produce positive photographic copies has been suggested. These fluorescent pigments emit visible light, which acts upon the sensitized surface to produce an. image which has essentially the same quality as a photographic copy.

it is among the objects of this invention to provide a process which produces an image or reproduction more closely resembling the original than a photographic copy h reof- 7 Another object of this invention is to provide such process which is sin iple to carry out and requires no expensive or complicated apparatus for its practice.

Still another object is to provide such process in, which the image is produced directly from the original, and without the use of a negative.

Still another object of this invention is to provide such process which permits the production of a large number of prints of uniform quality from a single original.

Still another object is to provide such process which gives. the artist great freedom in the choice of materials and surfaces upon which to work, and which results in the production of novel and desirable artistic effects heretofore not obtainable.

Other objects and advantages of this invention will be apparent from the following detailed description thereof.

In accordance with this invention a marking medium containing any desired pigment to impart a desired color to the marking medium along with a radioactive isotope (hereinafter referred to as a radioisotope) is employed to make the drawing to be reproduced, and which is hereinafter referred to as the original. It Will be understood the term drawing is used herein in a broad sense, and includes paintings and other forms of illustration or representation. The original is then exposed to a radiosensitive surface, which is thereafter developed and fixed to obtain directly a reproduction of the original. The original may thus be used repeatedly to produce any desired number of reproductions. Such use may be continued until the radioactivity of the radioisotope is diminished to the point where the sensitized surface is no longer activated to the extent necessary to produce satisfactory reproductions.

In preparing the marking medium one or more radioisotopes are mixed with a pigment, such as carbon black, methylene blue or gentian violet, etc. Any pigment which can be manipulated satisfactorily by the artist may be employed. The radioisotopes which can be used in thisprogess are those which emit low energy beta rays, i. e., beta rays which have an. energy not exceeding about 3 meion ele t n t nd a pha emitters, such as. polouium. Examples of such radioisotopes are hydrogen 3, carbon 14, sulfur 35, calcium 45, promethium 147, nickel 63 and polonium. These radioiso topes give good results, particularly from the standpoint of, reproducing more precisely the original. We have used satisfactorily carbon 14 in the form of barium carbonate, calcium 45 in the form of calcium chloride, sulfur 35 in the form of barium sulfide, promethium 147 in the form of promethium chloride and nickel 63 in the form of nickel chloride, all of which emit pure beta rays. These radioisotopes are produced in atomic piles, or by means of a cyclotron and may be obtained from the Atomic Energy Commission, Oak Ridge, Tennessee. it will be understood that this invention includes the use of such radioisotopes irrespective of how they are produced.

The proportions in which the radioisotope and pigment, preferably in the form of a solution thereof in a suitable solvent, may be mixed can vary within wide limits. In general the amount of pigment used will be that which the artist finds convenient for obtaining the desired effects.

Wide variations in the level of radioactivity can be tolerated since the original can be exposed to the radiosensitive surface for periods ranging from a few seconds to several weeks as may be required to produce a satisfactory image. With weak beta emitters, levels of radioactivity ranging from 0.3 to 1.0 millicuries per milliliter require exposure periods ranging from 1 to 8 days on photographic projection paper.

As a practical matter a radioisotope should not be used which has a level of radioactivity such that it might cause injury to the user. This will of course depend upon the type and energy of radiation. Those which emit low energy beta or alpha rays require no special safeguards; the skin offers adequate protection, and it is necessary only to protect the eyes with eyeglasses or goggles and to avoid ingestion of the radioactive material. By a low energy beta emitter is meant a radioisotope which has an energy not exceeding about 0.3 m. e. v. (million electron volts).

The original may be made with the radioactive ink or other marking material on any desired surface such as paper, cloth, glass, suitable plates comparable to plates of a letterpress or lithographic plates, and used directly to make reproductions on surfaces sensitive to radioactivity, as hereinafter disclosed. Thus, for example, the original may be produced by printing on any desired surface employing printing pastes or inks containing the radioisotope as hereinabove disclosed, or by applying the ink or other marking medium manually to any desired surface to produce, for example, a painting, or other work of art, illustration or representation.

The radiosensitive surface to which the original is es:- poscd may be any surface which has been coated, impregnated, or otherwise provided with a surface which can be activated by radiation. Thus paper, cellulose ester films, glass, or any other suitable surface may be provided with a surface layer of a gelatine emulsion containing finely divided silver halides, such as silver bromide, silver iodide, or silver chloride. The halide is present in such proportions as to impart the desired sensitivity to the surface. Such sensitive papers, in the form of photographic paper, plate or film, including X-ray film, are available commercially, and hence no further description thereof is necessary.

In the development and fixing of the image produced on the radiosensitive surface, any developer and fixing s lution used in ordinary photographic processes, can be used in the process of this invention. When employing photographic or other sensitized paper, film, or plate, the recommendations of the manufacturer thereof with respect to the developing and fixing solutions to be used therewith may be followed, and satisfactory results obtained. Variations in the developing and fixing solutions will produce variations in the grain size and tone of print. A representative formula for a stock solution, for use as a developer when employing photographic paper is as follows:

Water (125 F.) oz 16 p-monomethylamine-m-cresol sulfate grains 36 Hydroquinone do 146 Sodium sulfite, anhydrous "oz" 1% Sodium carbonate, anhydrous oz 1% Potassium bromide grains.. 73 Cold water to make oz 32 In the use of this stock solution, it is diluted 1 part stock solution to 2 parts water. The photographic paper may be developed from 2 to 5 minutes at approximately 68 F. until a suitable image is formed. The resultant print is then placed in an acid stop bath containing, for example, 32 oz. of water and 1 /2 oz. of acetic acid of 25% by weight concentration for approximately 1 minute. It is then placed in a hypo bath for not less than 29 minutes, and finally washed 1. hour in running tap water.

A representative hypo bath is as follows:

Water at 120 F oz 26 Sodium thiosulfate -oz 8 After above has dissolved mix with:

Water (120 F.) oz 2 /2 Sodium sulfite (anhydrous) oz /2 Acetic acid, 28% oz 1 /2 Potassium alum "02-- /2 In the process of this invention the image is created 'by the action of non-visible radiation which produces an image which differs in quality from a copy made photographically. This is due in part to the fact that the process of this invention is a direct one with no negative image formed, and in part because the quality of an image produced by ionizing radiation (beta rays, gamma rays, or alpha rays) difiers from that produced by nonionizing, visible radiation. Hence, this process produces artistic effects not obtainable by heretofore known photographic procedures. Furthermore, the process of this invention is versatile, because the quality of the image can be varied by using materials which emit different types of rays, or which emit rays of different energies, and also by using various surfaces for the original drawing.

The following examples are given for purposes of illustrating the invention. It will be understood that this invention is not limited to these examples.

Example I In the production of the marking media, sulfur '35 in the form of barium sulfide, in a barium hydroxide solution assaying approximately 17 millicuries per milliliter, was mixed with carbon black writing ink in the proportion of 2 milliliters of the radioactive sulfide solution per 8 milliliters of the pigment solution. A. drawing was made with this marking medium, using pen and brush. At the time this drawing was made the ink had a radioactivity of approximately 2.6 millicuries per milliliter.

The drawing was exposed to double weight photographic enlarging paper for 4 days. This was effected by placing the drawing, face down, on the sensitive surface of the photographic paper, and the two kept in close contact during the exposure period.

The resultant print was developed for approximately 5 minutes in a developer having the formula hereinabove given. It was then fixed in a standard hypo bath, as described above, for 20 minutes, and washed in running water for 1 hour. The print was dried between sheets of blotting paper and mounted by means or" dry mounting tissue. The resultant print was a mirror image reproduction of the original.

4 Example II Example III The marking medium used was the same as in Example II. The drawing made was on rough watercolor paper, by means of a brush. The drawing was exposed to X-ray film for 1 /2 hours and then developed for 4 minutes at 68 F. in the following developer solution:

Water, F oz '16 p-Monomethylamine-m-cresol chloride grains 15 Sodium sulfite, anhydrous oz 2 /2 Hydroquinone grains Sodium carbonate do 365 Potassium bromide do 73 Cold water to make oz 32 Thereafter it was placed in an acid stop bath of the composition disclosed in line 20, column 3, hereof, for approximately 1 minute, and then in a hypo bath for 20 minutes, and finally washed 1 hour in running tap water. The hypo bath used was the same as that here inabove disclosed. The resultant reproduction was a mirror image of the original drawing.

It will be noted this invention provides a process for producing an image or reproduction in which the image or reproduction is produced directly from the original, and without the use of a negative.

It will be further noted the process of this invention is simple, requires no expensive or complicated apparatus, and permits of the reproduction of a large number of prints of uniform quality from a single original. The process of our invention gives the artist great freedom in the choice of materials and surfaces upon which to work, and, hence, makes possible the production of a wide variety of artistic effects, some of which are unique.

It is to be understood that this invention is not restricted to the present disclosure otherwise than as defined by the appended claims. Thus, for example, the marking media may contain two or more radioisotopes, the number used depending on the effect desired.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

1. A reproducing process which comprises preparing an original work on a supporting surface employing as the medium of artistic expression a composition containing at least one pigment imparting a desired visible color tone to said composition and containing at least one radioactive material from the group consisting of polonium and beta emitters which emit beta rays having an energy not exceeding about 0.3 million electron volts to create on said surface a desired visible artistic effect including gradations of tone, exposing said original to a sensitized surface to produce an image of the original on said sensitized surface, and fixing the resultant image to obtain an accurate reproduction of said original including said gradations of tone.

2. The reproducing process as defined in claim 1, in which the radioactive material is an element from the group consisting of carbon 14, calcium 45, sulfur 35, polonium, promethium 147, nickel 63, and hydrogen 3, and a number of mirror copies of said original are obtained by repeatedly and successively exposing said original to sensitized surfaces to produce successive im ngrsoyaa 5 ages of the original on said surfaces and fixing the resultant image on each said surface.

3. The reproducing process as defined in claim '1, in which the radioactive material is sulfur 35 in the form of barium sulfide. 5 4. The reproducing process as defined in claim #1, in which the radioactive material is calcium 45 in the form of calcium chloride.

5. The reproducing process as defined in claim 1, in which the radioactive material is carbon 14. 10

6. The reproducing process as defined in claim 1,

in which the sensitized surface is a film sensitive to said radioactive material.

References Cited in the file of this patent UNITED STATES PATENTS Pecher June 2, 1941 De Ment Mar. 4, 1952 OTHER REFERENCES 

